This invention relates to a process and apparatus for operating an installation for the heat treatment of a product liquid on the continuous flow principle, the product liquid being brought to the required temperature in a high temperature HT heat-exchanger by a heating medium, the treated and outgoing product liquid pre-heating the incoming untreated product liquid in counter-current in a regenerative heat-exchanger. The abbreviated term HT heat-exchanger denotes a heat-exchanger, operative at the highest temperature.
Related processes and apparatus are frequently used, inter alia, for the sterilization of milk. During sterilization, milk must be heated for a specific period at a specific temperature in order to kill or inactivate bacteria which would cause spoilage. As the heating temperature rises, the heating time required decreases. The longer the heating period, the more effective sterilization, but there are limits to this, since the chemical transformation processes involved at elevated temperature result in undesirable quality changes in the milk if applied for too long.